Process of annealing steel.



- same.

are. reaeee.

Patented March 29, 1904.

lda'reit'r omen.

LEONARD D. DAVIS, or ERIE, PENNSYLVANIA.

assesses or" antiserum STEEL.

srncrrrcarrorr forming part of Letters meant are. 755,629, dated. March 29, 1904..

Application filed m 5, 1901.

To all whom it may concern:

. Be it known that I, LEONARD D. Davis, a citizen of the United States, residing at Erie, inthe county'of Erie and State of Pennsyl- Vania, have invented certain new and useful improvements in Processes of Annealing Steel; and Ido hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the This invention relates to a process of annealing steel; and it consists in certain improvements therein as will be hereinafter fully described. and pointed out in the claims.

Heretofore the process ordinarily used for annealing steel has been toheat the steel in an open furnace (where the steel is subjected tothe action of heated gases) to a temperature ranging from 1,200 to 1,500 Fahrenheit, according to the nature of the steel.

: Great difiicultyhas been experienced with this method in getting an even heat to all parts of the steel, especially articles of large size and 2 5 especially those of considerable length. This is particularly true in annealing tubing and Shaft 111g, which in the process of 'majgiufacture require annealing several times. With each annealing with the presentmethod there is a considerableloss through scaling, and there ,is not only this loss, but this scaling interferes with theproduction of a smooth article, so

much so that in many cases the metal requires pickling between the passes. I obviate largely, all these difficulties by providing a' molten metal bath, in which the steel to be annealed is immersed. This bath is heated to a temperature of about I, 200 to 1, 500 Fahrenheit,

depending on the nature of the metal to be annealed, and maintained at that temperature.

The steel to be annealed is immersed'in this i i bath and of course immediately takes up enough heat to bring it to the temperature of the molten metal. I prefer using a metal which fuses at nearly the point it is desired to heat the steel-that is, a metal that fuses .between 1,000 and 1,500 I have found that aluminium answers 'the purpose better than any metal with which I have" experi- Serial No. 67,228. (No model.)

mented, as the steel comes from it clearer than with most metals. It fuses at about the point that it, is desired to heat the steel, so that the right temperature is kept if the aluminium is simply kept in a molten static. The loss of scaling is very largely obviated. This is of great importance, so much so that under prescut methods: where pickling to remove the scaling is objectionable because'of the injury that it does to the metal, retort-annealing has been resorted to. This is an expensive method, and consists in heating the metal in a closed retort from whichthe oxygen'has been largely excluded. In some cases the retort has been used without the exclusion of air: but of course the oxygen present is soon exhausted, so that the scaling is reduced over what it is,

in the usual or ordinary method. It will also be noted that with moltenmetal-the temperature of one partof the mass is soon communian even heating of'the steel being annealed in all parts. This it will be readily understood is a great advantage. I prefer using practically pure aluminium or alloys in which aluminium predominates. By using aluminium 1 accomplish a further result incident to the chemical action of aluminium on steel. lylVhere the tubes are immersed l in aluminium, not only is the air excluded, so that-lie formation of thescale is reduced to a m1mmum,'but the action of the aluminium on steel tends to re move whateverscaleiinay be formed. What I claintas new is v 1'. The process of annealingsteel which consists in immersing steel in a bath of molten metal which fuses between 1,000 to 1,500

Fahrenheit and gradually cooling steel.

- cated to all parts of the'mass, so that there is no difliculty insecuring an even temperature to all parts ofthe molten mass. m This assures 2. The process of annealing steel which 201i;i

- sists of immersing it in a bath of molten meta in which aluminiu m predominates and which In testimony whereof I afix my signature in is heaaed 0 a gempelgiaturelofnfrom11,100 tlo' presence of two Witnesses! '1,500-Fa ren e-it an 'gra ha ycoo ing stee i w The process of annealing steelwhich con- LEONARD D '5 si'sts in immersingsteelin abath of aluminium -Witnes'ses: Y I

heated vto a temperature of from1.1,12;.'y to JUSTIN P. 'SLbcUM, 1,500 'Fahrenheit and gradually coolingsteel. H. Z. LORD; 

